This invention relates to a breech assembly for an electrothermal gun, a gun provided with such a breech assembly and an obturation assembly for a gun.
A conventional tilting block assembly for a gun such as a cannon or the like, comprises a spindle having a shaft and a mushroom shaped head; and an obturation set including a resilient obturator pad for mating with and sealing against an obturation seat, an inner ring and two retaining rings. The obturation seat is usually defined by the rim of the mouth of a barrel at the rear end of the firing chamber. When the spindle is displaced axially relative to the barrel by the combustion of a propellant charge in the firing chamber, the obturator pad deforms radially outwardly into sealing engagement with the obturation seat, with the retaining rings limiting deformation of the obturator pad and preventing extrusion of the obturator pad.
The tilting block assembly is usually held in position by a crank arm and rollers, which are supported by the breech ring of the gun and the shaft of the spindle usually extends through a hole in the tilting block assembly abutting a sliding block. Although this application is for the loading and firing of a front loaded plasma generator cartridge (PGC), it is also possible to machine a chamber in the rear end of the spindle for a cased primer for igniting the propellant charge, and a so called primer head space is defined between the rear end of a primer case and the front face of the sliding block.
It is known to use a plasma generator cartridge (PGC) to generate plasma when high-voltage is applied thereto. Various examples of PGC's and/or electrothermal chemical (ETC) applications are disclosed in the following U.S. Pat. Nos. 4,640,180 4,895,062 5,042,359 5,171,932 5,183,956 5,612,506 5,675,115 5,898,124 5,945,623 5,988,070.
A common disadvantage of all the above arrangements is that the PGC is loaded from the rear into a carrier mechanism, such as a stub case or spindle arrangement, causing sealing problems between the PGC and the carrier mechanism. Another disadvantage is that the rear inserted PGC increases the time required for loading the PGC and charge during sustained and rapid fire. The use of cases for the main obturation and PGC carrier, further increases the overall operational cost per fired shot. Further disadvantages of the known systems are that the PGC's and stub cases are strewn around the inside the turret of the gun and that the sealing efficiencies of the known obturation assemblies are not reliable.